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Maintaining a geographical frame of reference
An inset map is a smaller map to help the user maintain a geographical frame of
reference. The overview map is synchronized with thebounds_changedevent on
the main map.
TypeScript
constOVERVIEW_DIFFERENCE=5;constOVERVIEW_MIN_ZOOM=3;constOVERVIEW_MAX_ZOOM=10;functioninitMap():void{constmapOptions={center:{lat:50,lng:8},zoom:7,};// instantiate the primary mapmap=newgoogle.maps.Map(document.getElementById("map")asHTMLElement,{...mapOptions,});// instantiate the overview map without controlsoverview=newgoogle.maps.Map(document.getElementById("overview")asHTMLElement,{...mapOptions,disableDefaultUI:true,gestureHandling:"none",zoomControl:false,});functionclamp(num,min,max){returnMath.min(Math.max(num,min),max);}map.addListener("bounds_changed",()=>{overview.setCenter(map.getCenter()!);overview.setZoom(clamp(map.getZoom()!-OVERVIEW_DIFFERENCE,OVERVIEW_MIN_ZOOM,OVERVIEW_MAX_ZOOM));});}declareglobal{interfaceWindow{initMap:()=>void;}}window.initMap=initMap;
constOVERVIEW_DIFFERENCE=5;constOVERVIEW_MIN_ZOOM=3;constOVERVIEW_MAX_ZOOM=10;functioninitMap(){constmapOptions={center:{lat:50,lng:8},zoom:7,};// instantiate the primary mapmap=newgoogle.maps.Map(document.getElementById("map"),{...mapOptions,});// instantiate the overview map without controlsoverview=newgoogle.maps.Map(document.getElementById("overview"),{...mapOptions,disableDefaultUI:true,gestureHandling:"none",zoomControl:false,});functionclamp(num,min,max){returnMath.min(Math.max(num,min),max);}map.addListener("bounds_changed",()=>{overview.setCenter(map.getCenter());overview.setZoom(clamp(map.getZoom()-OVERVIEW_DIFFERENCE,OVERVIEW_MIN_ZOOM,OVERVIEW_MAX_ZOOM,),);});}window.initMap=initMap;
/** Always set the map height explicitly to define the size of the div element* that contains the map.*/#map{height:100%;}/** Optional: Makes the sample page fill the window.*/html,body{height:100%;margin:0;padding:0;}#container,#map{height:100%;width:100%;}#map{position:relative;}#overview{position:absolute;left:40px;height:175px;width:175px;bottom:50px;box-shadow:02px6pxrgba(0,0,0,0.3);}
<html>
<head>
<title>Inset Overview Map</title>
<link rel="stylesheet" type="text/css" href="./style.css" />
<script type="module" src="./index.js"></script>
</head>
<body>
<div id="container">
<div id="map"></div>
<div id="overview"></div>
</div>
<!--
The `defer` attribute causes the script to execute after the full HTML
document has been parsed. For non-blocking uses, avoiding race conditions,
and consistent behavior across browsers, consider loading using Promises. See
https://developers.google.com/maps/documentation/javascript/load-maps-js-api
for more information.
-->
<script
src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&v=weekly"
defer
></script>
</body>
</html>
Git and Node.js are required to run this sample locally. Follow theseinstructionsto install Node.js and NPM. The following commands clone, install dependencies and start the sample application.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 UTC."],[[["\u003cp\u003eThis sample demonstrates how to create an inset map, providing a smaller overview map synchronized with a main map for better user orientation.\u003c/p\u003e\n"],["\u003cp\u003eThe overview map automatically adjusts its center and zoom level based on the main map's changes, using a predefined zoom difference and limits.\u003c/p\u003e\n"],["\u003cp\u003eThe sample includes code in TypeScript, JavaScript, CSS, and HTML, showcasing the implementation of the inset map functionality.\u003c/p\u003e\n"],["\u003cp\u003eThe overview map is positioned and styled using CSS to appear as an inset element within the main map container.\u003c/p\u003e\n"],["\u003cp\u003eUsers can interact with the main map, while the overview map passively reflects those changes, offering a broader geographical context.\u003c/p\u003e\n"]]],[],null,["Maintaining a geographical frame of reference\n\nAn inset map is a smaller map to help the user maintain a geographical frame of\nreference. The overview map is synchronized with the `bounds_changed` event on\nthe main map. \n\nTypeScript \n\n```typescript\nconst OVERVIEW_DIFFERENCE = 5;\nconst OVERVIEW_MIN_ZOOM = 3;\nconst OVERVIEW_MAX_ZOOM = 10;\n\nfunction initMap(): void {\n const mapOptions = {\n center: { lat: 50, lng: 8 },\n zoom: 7,\n };\n\n // instantiate the primary map\n map = new google.maps.Map(document.getElementById(\"map\") as HTMLElement, {\n ...mapOptions,\n });\n\n // instantiate the overview map without controls\n overview = new google.maps.Map(\n document.getElementById(\"overview\") as HTMLElement,\n {\n ...mapOptions,\n disableDefaultUI: true,\n gestureHandling: \"none\",\n zoomControl: false,\n }\n );\n\n function clamp(num, min, max) {\n return Math.min(Math.max(num, min), max);\n }\n\n map.addListener(\"bounds_changed\", () =\u003e {\n overview.setCenter(map.getCenter()!);\n overview.setZoom(\n clamp(\n map.getZoom()! - OVERVIEW_DIFFERENCE,\n OVERVIEW_MIN_ZOOM,\n OVERVIEW_MAX_ZOOM\n )\n );\n });\n}\n\ndeclare global {\n interface Window {\n initMap: () =\u003e void;\n }\n}\nwindow.initMap = initMap;https://github.com/googlemaps/js-samples/blob/2683f7366fb27829401945d2a7e27d77ed2df8e5/samples/inset-map/index.ts#L9-L56\n```\n| **Note:** Read the [guide](/maps/documentation/javascript/using-typescript) on using TypeScript and Google Maps.\n\nJavaScript \n\n```javascript\nconst OVERVIEW_DIFFERENCE = 5;\nconst OVERVIEW_MIN_ZOOM = 3;\nconst OVERVIEW_MAX_ZOOM = 10;\n\nfunction initMap() {\n const mapOptions = {\n center: { lat: 50, lng: 8 },\n zoom: 7,\n };\n\n // instantiate the primary map\n map = new google.maps.Map(document.getElementById(\"map\"), {\n ...mapOptions,\n });\n // instantiate the overview map without controls\n overview = new google.maps.Map(document.getElementById(\"overview\"), {\n ...mapOptions,\n disableDefaultUI: true,\n gestureHandling: \"none\",\n zoomControl: false,\n });\n\n function clamp(num, min, max) {\n return Math.min(Math.max(num, min), max);\n }\n\n map.addListener(\"bounds_changed\", () =\u003e {\n overview.setCenter(map.getCenter());\n overview.setZoom(\n clamp(\n map.getZoom() - OVERVIEW_DIFFERENCE,\n OVERVIEW_MIN_ZOOM,\n OVERVIEW_MAX_ZOOM,\n ),\n );\n });\n}\n\nwindow.initMap = initMap;https://github.com/googlemaps/js-samples/blob/2683f7366fb27829401945d2a7e27d77ed2df8e5/dist/samples/inset-map/docs/index.js#L8-L46\n```\n| **Note:** The JavaScript is compiled from the TypeScript snippet.\n\nCSS \n\n```css\n/* \n * Always set the map height explicitly to define the size of the div element\n * that contains the map. \n */\n#map {\n height: 100%;\n}\n\n/* \n * Optional: Makes the sample page fill the window. \n */\nhtml,\nbody {\n height: 100%;\n margin: 0;\n padding: 0;\n}\n\n#container,\n#map {\n height: 100%;\n width: 100%;\n}\n\n#map {\n position: relative;\n}\n\n#overview {\n position: absolute;\n left: 40px;\n height: 175px;\n width: 175px;\n bottom: 50px;\n box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);\n}\nhttps://github.com/googlemaps/js-samples/blob/2683f7366fb27829401945d2a7e27d77ed2df8e5/dist/samples/inset-map/docs/style.css#L17-L53\n```\n\nHTML \n\n```html\n\u003chtml\u003e\n \u003chead\u003e\n \u003ctitle\u003eInset Overview Map\u003c/title\u003e\n\n \u003clink rel=\"stylesheet\" type=\"text/css\" href=\"./style.css\" /\u003e\n \u003cscript type=\"module\" src=\"./index.js\"\u003e\u003c/script\u003e\n \u003c/head\u003e\n \u003cbody\u003e\n \u003cdiv id=\"container\"\u003e\n \u003cdiv id=\"map\"\u003e\u003c/div\u003e\n \u003cdiv id=\"overview\"\u003e\u003c/div\u003e\n \u003c/div\u003e\n\n \u003c!-- \n The `defer` attribute causes the script to execute after the full HTML\n document has been parsed. For non-blocking uses, avoiding race conditions,\n and consistent behavior across browsers, consider loading using Promises. See\n https://developers.google.com/maps/documentation/javascript/load-maps-js-api\n for more information.\n --\u003e\n \u003cscript\n src=\"https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&v=weekly\"\n defer\n \u003e\u003c/script\u003e\n \u003c/body\u003e\n\u003c/html\u003ehttps://github.com/googlemaps/js-samples/blob/2683f7366fb27829401945d2a7e27d77ed2df8e5/dist/samples/inset-map/docs/index.html#L8-L33\n```\n\nTry Sample \n[JSFiddle.net](https://jsfiddle.net/gh/get/library/pure/googlemaps/js-samples/tree/master/dist/samples/inset-map/jsfiddle) [Google Cloud Shell](https://ssh.cloud.google.com/cloudshell/editor?cloudshell_git_repo=https%3A%2F%2Fgithub.com%2Fgooglemaps%2Fjs-samples&cloudshell_git_branch=sample-inset-map&cloudshell_tutorial=cloud_shell_instructions.md&cloudshell_workspace=.)\n\nClone Sample\n\n\nGit and Node.js are required to run this sample locally. Follow these [instructions](https://docs.npmjs.com/downloading-and-installing-node-js-and-npm) to install Node.js and NPM. The following commands clone, install dependencies and start the sample application. \n\n git clone -b sample-inset-map https://github.com/googlemaps/js-samples.git\n cd js-samples\n npm i\n npm start\n\n\nOther samples can be tried by switching to any branch beginning with `sample-`\u003cvar translate=\"no\"\u003eSAMPLE_NAME\u003c/var\u003e. \n\n git checkout sample-\u003cvar translate=\"no\"\u003e\u003cspan class=\"devsite-syntax-nx\"\u003eSAMPLE_NAME\u003c/span\u003e\u003c/var\u003e\n npm i\n npm start"]]
